Manually operated fuel control valves for vehicles, such as motorcycles, are typically constructed for operating at two or three positions of the valve. An "on" position for use when the fuel tank is full, and a "reserve" position when the fuel tank is nearly depleted and possibly a third "off" position closing the valve against flow of fuel. To control the position of the valve, a manually operable valve control is provided. When fuel in the tank lowers to a prescribed level, the fuel inlet for the "on" position rises above the level of fuel. With no more fuel going through the valve the engine stops and the operator is immediately warned to shift the control valve to the "reserve" position. The user now knows that there is a minimal amount of fuel in the tank and that filling is required.
Valves of the type described above may also include a third "off" position for the valve control wherein the valve is shut off completely against the flow of fuel. This third "off" position is advantageous as a safety feature and also permits repair work to be done on the engine without disconnecting the fuel supply.
Typically, the operation of the valve between the two fuel feeding positions is affected by rotation of the valve control, whereas movement of the valve o control to the third position closing the valve is an axial movement. A valve as described above, is disclosed in U.S. Pat. No. 4,250,921.
Prior valve constructions of the type described above, although providing a degree of warning to the user that the fuel tank is nearly depleted, do so by completely cutting off the supply of fuel and by requiring the operator to shift the valve to the reserve position before the flow of fuel is recommenced. This can, to say the least, be disconcerting. It may also cause stalling of the engine to which the fuel is supplied. If the valve is not immediately attended to and adjusted, this immediate requirement may be of some danger to the motorcyclist, depending on the situation in which it occurs.
The valves described above are typically mounted on the bottom of the fuel tank for gravity feed of the fuel through the valve and to the motorcycle engine. A portion of the valve is exposed externally of the fuel tank for control by the motorcyclist. In an accident or other mishap where the exposed valve portion receives a sharp impact blow or other damaging force, it can be broken away from the fuel tank. This in turn will permit the free escape of fuel from the tank, thus producing an obviously dangerous situation.